Method of making a suturing member and mounting the suturing member on a device

ABSTRACT

A suturing member and method of making the suturing member on an implantable prosthetic device, as a heart valve. The suturing member has a porous fabric cover surrounding a semi-rigid plastic core. An annular sleeve of heat shrinkable plastic material is located within the cover to hold the cover in assembled relation with the device in a manner which allows for rotation of the device after the suturing member has been attached to the tissue. The seam of the cover is located between the annular sleeve and the device. In the method of making the suturing member, the cover is located around the core and annular sleeve before it is mounted on the device. After the suturing member is mounted on the device, it is heated to cure the plastic core, bond the core to the inner surface of the cover, and heat shrink the sleeve around the device.

United States Patent [1 1 Anderson et a1.

[ 1 Apr.2,1974

[73] Assignee: Medical Incorporated, Minneapolis,

3,365,728 1/1968 Edwards et a1. 3/1

3,587,115 6/197] Shiley 3/1 3,594,824 7/1971 Nakib 31/] 3,619,47811/1971 Staiger 264/230 X 3,623,212 11/1971 Child 29/445 PrimaryExaminer-Charlie T. Moon [57] ABSTRACT A suturing member and method ofmaking the suturing member on an implantable prosthetic device, as aheart valve. The suturing member has a porous fabric cover surrounding asemi-rigid plastic core. An annular sleeve of heat shrinkable plasticmaterial is located within the cover to hold the cover in assembledrelation with the device in a manner which allows for rotation of thedevice after the suturing member has been attached to the tissue. Theseam of the cover is located between the annular sleeve and the device.In the method of making the suturing member, the cover is located aroundthe core and annular sleeve before it is mounted on the device. Afterthe suturing member is mounted on the device, it is heated to cure theplastic core, bond the core to the inner surface of the cover, and heatshrink the sleeve around the device.

14 Claims, 18 Drawing Figures PATENTEMPR 21914 3.800403 SHEEI 2 0F 3PATENTEDAPR 2W HEET 3 UF 3 1 METHOD OF MAKING A SUTURING MEMBER ANDMOUNTING TIIE SUTURING MEMBER ON A DEVICE BACKGROUND OF THE INVENTIONthe disc is in the open position, it is inclined at a slight angle so asto provide some direction to the centralized flow of blood leaving thevalve. During the implant procedure of a pivoting disc heart valve, itis often desirable to adjust the angular position of the valve after itis implanted. The base of the valve is rotated relative to the suturingmember secured to the heart tissue to orient the disc away fromcalcifications that could interfere with the free movement of the discand to direct the flow of blood in a selected direction. The valve baseis rotated relative to the suturing member with a holder or handle usedto position the valve during the implant procedure. Heretofore, in orderto permit angular orientation of the valve after implantation thesuturing member was provided with a relatively loose fit on the valvebase. The loose relationship between the suturing member and the valvebase is undesirable because in use the valve may shift or slide relativeto the suturing member and blood can accumulate adjacent the valve.

Suturing members are retained on the bases or housings of the heartvalves in a number of ways. A clamp ring and wire is disclosed in U. S.Pat. No. 3,099,016 to hold the sewing ring on the valve base. Astainless steel ring encased in porous material is used in U. S. Pat.No. 3,396,409 to hold the porous material on the base of the heartvalve. Child in U. S. Pat. No. 3,623,212 discloses a suturing member ona device. The cover is held on the valve base with a plurality of cordsor threads. The threads are wound in relatively close and tightrelationship and inhibit effective rotation of the valve base relativeto the suturing member once the threads are tied. The threads do notprovide for substantially even holding force across the entire width ofthe suturing member whereby portions of the suturing member can separatefrom the valve base.

SUMMARY OF THE INVENTION The invention is directed to a suturing memberfor an implantable device, as a heart valve, and a method of making thesuturing member on the device. The suturing member is an annularsuturing ring or collar that is mounted on a device in a mariner thatallows for circumferential movement or rotation of the device after thesuturing member has been attached to the tissue. The suturing member hasa cover located around a core of plastic material. The cover can be aseamless cylindrical fabric member. Located within the cover is anannular sleeve or tubular member of heat shrinkable plastic material.The sleeve is heat shrunk to provide a uniform contraction force to holdthe suturing member on the device. The annular seam of the cover islocated between the sleeve and the device, whereby the exposed portionsof the cover are continuous or seamless.

The suturing member is made by enclosing the core and sleeve within thecover. This assembly is then placed about the device, shaped and heatcured in a mold. During the curing, the core is bonded to the inside ofthe cover and the sleeve is heat shrunk about the device.

An object of the invention is to provide an implantable device with asuturing member that permits rotation of the device after the suturingmember has been attached to the tissue. Another object of the inventionis to provide a suturing member that does not have any seams exposed tothe tissue and that does not separate from the device. A further objectof the invention is to provide a method of making a suturing member on adevice which uniformly holds the suturing member on the device and bondsthe core material and suturing member to the cover. Still a furtherobject of the invention is to provide a suturing member which can beformed on a device in a variety of shapes and which can be applied tomany types of implantable devices.

IN THE DRAWINGS FIG. 1 is a top plan view of a heart valve and asuturing member of the invention mounted on the base of the heart valve;

FIG. 2 is a sectional view taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged sectional view of a portion of the base of theheart valve and suturing member;

FIG. 4 is an enlarged sectional view of an outer edge portion of thevalve disc;

FIG. 5 is a foreshortened plan view of a blank of the fabric cover ofthe suturing member;

FIG. 6 is a perspective view of the fabric cover in cylindrical form;

FIG. 7 is a transverse sectional view of the cylindrical cover around anannular core of uncured plastic material positioned adjacent the outsideof a heat shrinkable sleeve;

FIG. 8 is a view similar to FIG. 7 showing the cover enclosing the coreand sleeve with the cover seam on the inside of the suturing member;

FIG. 9 is a reduced scale sectional view taken along the line 9-9 ofFIG. 8;

FIG. 10 is a sectional view of the suturing member mounted on the baseof a heart valve prior to forming and curing of the core of plasticmaterial and heat shrinking of the sleeve;

FIG. 11 is a sectional view showing the heart valve and suturing memberlocated in the forming, heat shrink and curing mold for the suturingmember;

FIG. 12 is a perspective view of a seamless cylindrical fabric cover ofa modified suturing member of the invention;

FIG. 13 is a transverse sectional view of the cylindrical cover aroundan annular core of uncured plastic material located adjacent the outsideof a heat shrinkable sleeve;

FIG. 14 is a view similar to FIG. 13 showing the cover enclosing thecore and sleeve;

FIG. 15 is a reduced scale plan view, partly sectioned, of FIG. 14;

FIG. 16 is a sectional view of the suturing member mounted on the baseof a heart valve prior to positioning of the cover;

FIG. 17 is a view similar to FIG. 16 showing the cover seam positionedbehind the sleeve; and

FIG. 18 is a sectional view showing the heart valve and suturing memberlocated in the forming, heat shrink and curing mold for the suturingmember.

Referring to the drawings, there is shown in FIGS. 1 to 4 a heart valve20 for controlling the flow of blood. Valve 20 has a base or annularhousing 21 associated with a movable disc 22 to control the flow ofblood through the base. Disc 22 is a valving member or occluder thatangularly moves from a closed position, shown in full lines in FIG. 2,to an open position, shown in broken lines, and back to the closedposition in response to differential blood pressure on opposite sides ofthe valve. Disc 22 is retained in free floating relationship with thebase 21 whereby it is free to rotate about its center axis as it shiftsand angularly moves between its open and closed positions. The rotationof the disc as it pivots eliminates localized sites of wear and fatigueby avoiding localized or isolated breakdown of the valve structure. Asshown in FIG. 2, when the disc is in the open position, the blood isfree to flow adjacent opposite sides of the disc 22. The blood flowingadjacent opposite surfaces of the disc washes the disc without atemporary sinus on the distal side of the disc.

Base 21 has an outer annular side wall 23. Wall 23 has a cylindricalsurface located between an upper outwardly directed annular flange 24and a lower outwardly directed annular flange 25. A suturing member, orsewing collar, indicated generally at 26 surrounds side wall 23 toprovide structure for receiving sutures used to attach the valve to theheart tissue. Suturing member 26 is mounted on base 21 in a manner sothat base 21 can be rotated relative to the suturing member 26 after themember has been attached to the heart tissue. This permits the surgeonto adjust the angular position of the valve after it has been implantedin the heart. Pivoting disc 22 can be oriented away from calcificationswhich may interfere with the free movement of disc 22. As shown in FIG.2, when disc 22 is in the open position, it is at a slight anglerelative to the longitudinal axis of passage 28. The angularlypositioned disc directs the outflowing blood at a slight angle. Thedirection of the outflowing blood can be changed by the surgeon byrotation of the valve base relative to the attached suturing member 26,thereby providing optimum direction of the centralized flow pattern ofthe blood.

Base 21 has an inside, generally cylindrical wall 27 surrounding apassage or opening 28 through the base. Disc 22 is positionable in oroperatively located in passage 28 to permit free centralized andstreamlined flow of blood through passage 28 when the disc 22 is in theopen position and restrict reverse flow of blood through the passage 28when the disc 22 is in the closed position. Disc 22 is a flat circularmember having a circular continuous or uninterrupted outer peripheraledge 29. The outer peripheral edge 29 has an annular uninterruptedcircumferential configuration and is joined to a substantially flat topor distal surface 31 and a substantially flat bottom or proximal surface32.

Referring to FIGS. 1 and 2, the disc 22 is slightly smaller than thediameter of the opening 28 when the disc is in the closed position. Thisleaves a small annular space 33 between the outer peripheral edge 29 andthe adjacent circumferential portion of the inside wall 27 of the base.This annular space 33 permits limited reverse flow of blood through thevalve opening 28 past the edge 29 when the disc 22 is in the closedposition.

Reverse flow of blood prevents stagnation of blood in pockets or poolsadjacent the valve base as the blood is continuously moving throughpassage 28.

Pivot structures, indicated generally at 34 in FIG. 1, cooperate withthe disc 22 to control its pivotal movement and limit its open andclosed positions. Pivot structures 34 provide the disc 22 with a pivotaxis that is offset from the diameter of passage 28 so that when thedisc is in the open position, there is free centralized flow of bloodthrough passage 28. The pivot axis for the disc 22 generally follows animaginary or reference chord line approximately an equal distancebetween the center of passage 28 and the inside wall 27 measured along atransverse diametrical line, as section line 2-2 in FIG. 1. The pivotalaxis of the disc can vary, or shift, relative to the center of the discduring the opening and closing episodes as the disc 22 has limitedmovement in its plane and in a direction normal to the plane of thedisc.

Pivot structures 34 comprise upper or distal members or elements 36 and37 located adjacent circumferentially spaced portions of the distal sideof the disc 22 and project into opening 28. Located generally adjacentthe upper members 36 and 37 are lower or proximal members or elements 38and 39. Members 38 and 39 project into passage 28 and extend adjacentcircumferentially spaced portions of the proximal side 32 of the disc22. Pivot members 36 and 38 are pairs of projections or legs havingpivot surfaces which function as fulcrums for the disc 22 during itsopening and closing movements. Members 37 and 39 are a second pair ofprojections or legs having pivot surfaces for the disc during itsopening and closing movements. The pivot surfaces of the pairs of legscooperate with each other to define the pivoting and free floatingmovement of the disc.

As shown in FIG. 1, the outer peripheral edge 29 of the disc 22 isspaced from the inside wall portions of the base 21 between the pairs oflegs 36,38 and 37,39 with spaces 33A. Spaces 33A permit limited reverseflow of blood through the pivoting regions of the valve. Reverse flowprevents clot buildup and freezing at the pivoting areas. The reverseflow also washes the pivoting or fulcrum surfaces on the legs, therebypreventing clot formation on these surfaces. The washing of the pivotalregions is also aided by the rotation of the disc about its axis. Thefluid boundary layer on the disc is swept past the pivoting surfaces.

Members 37 and 39 are identical to members 36 and 38. The followingdetailed description is limited to members 36 and 38 since members 37and 39 have the same detailed structure. As shown in FIG. 2, proximalpivot member 38 has a round fulcrum corner 41 joined to a top inclinedface 42 and a generally upright face 43. Pivot member 36 has a fulcrumcorner 44 facing the top face of disc 22 joining the top inclined face46 and generally upright face 47. Faces 43 and 47 are generally parallelto each other. When disc 22 is in the closed position, face 46 is spacedfrom the distal surface 31 of the disc. This permits the disc 22 tofloat up and with the blood away from face 42 during the initial openingmovements of the disc 22. Midway between the lower members 38 and 39 isan upwardly directed stop or abutment 48 on housing 21 adapted to engagean outer peripheral portion of disc 22. The lower members 38 and 39 andstop 48 serve to support the disc in a generally inclined position withrespect to the longitudinal axis of the passage 28 when the disc is inthe closed position. Preferably this incline is about 18 from thehorizontal plane of the base.

The disc 22 is maintained in free floating assembled relation withrespect to the pivot structures 34 with retaining arms or members 49 and51. The arms 49 and 51, integral with the top of base 21, projectupwardly and are inclined from the base in the direction of pivotalmovement of the disc 22. The arms 49 and 51 each have inside surfaces orfaces 52 and 53 which have a concave curvature larger than the curve orare of the outer peripheral edge of the disc 22. The surfaces 52 and 53curve inwardly toward the center line of the disc, as shown in FIG. 1,and are located outwardly of or above the diameter of the disc 22 sothat the disc is retained in assembled relation with the base at allpositions between its open and closed positions. The surfaces 52 and 53follow a helical or spiral path as the radius of the arc of the surfaces52 and 53 increases toward the outer ends of the arms. The curvature ofthe surfaces 52 and 53 approaches the curvature of the pivot arc of thedisc when the disc is in the closed position. This structure permits thedisc to float and move upwardly during its opening episode, as indicatedin FIG. 2.

FIG. 4 is an enlarged cross section of a portion of the disc 22 showingthe disc substrate 54 entirely covered with a Pyrolite carbon coating orskin 56. A Pyrolite carbon substrate bond 57 firmly and positively joinsthe coating 56 to the substrate 54. For example, the substrate 54 can bea polycrystalline graphite coated with silicon alloyed Pyrolite carbon.The carbon coating can have a Pyrolite carbon prime layer covered with aPyrolite carbon finish coat. The silicon-alloyed Pyrolite carbon isdeposited at low temperatures in two layers. The thermal coefficient ofexpansion of the substrate graphite is such that during the coolingafter coating, the outer carbon layer is forced into a compressive stateof stress which enhances the toughness and wear characteristics of thecoating. The Pyrolite carbons are deposited in a fluidized bed from ahydrocarbon containing gaseous environment. These carbons are strongerand tougher than other bulk forms of carbon. The coatings can be appliedto a variety of substrates including metal, ceramics and graphite. Thesubstrates can have complex shapes without danger of delamination andcracking.

Referring to FIG. 3, the suturing member 26 has an outwardly directedannular flange 26A and an upwardly directed body terminating in a distalannular ridge 268. Ridge 268 extends above the top of valve base 21.Suturing member 26 has a cover of fabric made of synthetic fibers, asTeflon or "Dacron cloth or the like. The fabric of cover 57 isbiologically inert porous material which can accommodate live tissueingrowth or fibrosis between the tissue and the porous material. Cover57 surrounds an elastic core 58 of plastic material, as silicone, DowCorning Silastic, fluorosilicone rubber or similar synthetic resinousplastic material. The inside of cover 57 is bonded to the entire outersurface 59 of the core 58, thereby preventing separation of the coverfrom the core and eliminating voids or pockets which can accumulateblood. The turned edge portions of cover 57 are secured together withstitches 61 forming a seam and are located adjacent the mid-section ofthe outside wall 23 of valve base 21. An annular circular sleeve,collar, or tubular member 62 is located around the stitched end portionsof cover 57 and between the core 58 and the stitched end portions.Sleeve 62 has a width generally equal to the width of the outside wall23 of the base 21 so as to hold the inside portion of the cover 52between flanges 24 and 25 in surface engagement with the wall 23. Theends of sleeve 62 have outwardly projected annular portions or ribs 62Aand 6213. The ribs 62A and 628 have outwardly diverging outside wallswhich are generally parallel to adjacent inside faces of flanges 24 and25. Sleeve 62 provides a uniform circumferential holding force for thecover on the base which permits rotation of the valve base 21 relativeto the suturing member 26. Sleeve 62 is preferably of heat shrinkableplastic material, as Teflon, so that when heat shrunk around the valvebase 21 it provides a relatively uniform circumferential andlongitudinal fit of the suturing member 26 on the base 21. The sleeve62, being lo cated over the stitched end portions and stitches 61,protects stitches 61 from the sutures used to attach the suturing member26 to the heart tissue.

Referring to FIGS. 5 to 11, there is shown the process of making andmounting the suturing member 26 on the valve base 21. FIG. 5 shows thecover 57 cut to a rectangular shaped blank of selected size determinedby the size of the valve base 21. Preferably, the fabric of cover 57 iscut on a bias, as a 45 angle. The fabric blank then is formed into acylinder or tube, as shown in FIG. 6. The adjacent ends of cover 57 arestitched together with stitches 63. Cover 57 can be a seamlesscylindrical member as shown in FIG. 12.

Referring to FIG. 7, the core 58 of uncured plastic material is placedaround the sleeve 62. Sleeve 62 is a tubular member that is pre-shrunkon a cylindrical mandrel to a selected size or diameter. Cover 57 isturned inside out and placed over the core 58 with the ends of thecylinder formed by stitches 63 facing the core. The uncured plasticmaterial 58 can be formed into an elongated roll and uniformly placedaround sleeve 62 between ribs 62A and 628. The plastic material of thecore, being uncured and relatively pliable, does not interfere with theplacing of cover 57 around the core. Preferably a roll of plasticmaterial is weighed so that a determinant amount of plastic material canbe placed around sleeve 62.

Referring to FIG. 8, the upper and lower ends of the cover 57 are turnedin and folded over the sleeve 62. This encloses the core 58 and sleeve62 within cover 57. The ends of cover 57 are stitched together withstitches 61. This places the turned ends or seam of the cover 57 and thestitches 61 midway along the inside of sleeve 62. As shown in FIG. 9,stitches 61 extend circumferentially around the inner side of sleeve 62.Double box stitches 64 and 66 are placed in the cover 57 adjacent theopposite ends of the sleeve 62. The stitches 61 have ends 61A and 61Bannularly woven through the cross stitches and extended through thesleeve 62, core 58 and cover 57.

Suturing member 26 is then mounted on valve base 21. This is done byslipping the sleeve 62 and cover 57 over the flange 25 locating thesleeve in groove 23 between flanges 24 and 25. Stitches 61 and thefolded ends of cover 57 are located in engagement with the inside wall23 of the valve base 21. The sleeve 62 is lo cated between flanges 24and 25, with the ribs 62A and 628 located adjacent the inside portionsof flanges 24 and 25 to hold cover 57 in engagement with the cylindricalsurface of wall 23. The ends 61A and 61B of stitches 61 are pulled andtied with a slip lock knot adjacent sleeve 62. The ends of stitches 64and 66 are then pulled and tied to firmly anchor the cover 57 to thevalve base adjacent the flanges 24 and 25. Stitches 61, 64 and 66 serveas wrappings to ensure that the suture member 26 will retain itsposition on the valve base 21 and still permit rotation of the valvebase 21 relative to the suturing member 26.

Referring to FIG. 11, there is shown a curing mold 67 for shaping thesuturing member 26 and holding the suturing member during curing of thecore 58. Mold 67 has a center cavity 68 accommodating valve 20. Theupper portion of cavity 68 is enlarged and has an annular stepped groove69 defining the final shape of suturing member 26. The annular groove 69is surrounded with an annular stepped wall 71. The cavity 68 and groove69 are closed with a flat plate or cover 72. Interposed between plate 72and an outer circumferential portion of the suturing member 26 is a ring73 which has a shape to provide the annular flange 26A of the suturingmember 26 with a tapering or narrower outer peripheral edge. The plate72 holds the ring in engagement with suturing member 26. Suitable clampmeans or fasteners (not shown) secure the plate 72 to mold 67. Thepressure exerted by plate 72 and ring 73 on the. suturing member 26forces the pliable uncured plastic core 58 into surface engagement withthe fabric of the cover 57. The shape of the annular stepped wall 71 andthe surface of the plate 72 along with the shape of ring 73 determinesthe ultimate shape of suturing member 26. Mitral and aortic suturingmembers can be made with molds having different shaped grooves andcontours.

Suturing member 26 mounted on valve base 21, as shown in FIG. 10, ispressed into mold groove 69. This changes the shape of suturing member26 conform to the shape of the mold groove 69. As shown in FIG. 1 l, thesuturing member 26 is positioned in the groove with a light force fit sothat cover 57 is in continuous engagement with the plastic core 58. Theuncured plastic core 58 is cured by heating the mold for a period oftime. For example, suturing member 26 is heated for about minutes at 250F. Other temperatures and times are used in accordance with the heatcuring characteristics of the plastic. During heat curing, the core 58bonds to the inside surface of the cover to form a continuous andpermanent connection or bond 59 between the core 58 and cover 57. Thebond 59, being continuous, eliminates pockets or spaces between thecover 57 and core 58. Also, the bond eliminates the possibility ofseparation of the cover 57 from the core 58 which can provide space forcollection of blood and other body fluids. During the heat curingprocess, the core 58 does not penetrate the porous fabric or cover 57.Accordingly, the plastic core does not interfere with tissue ingrowthinto the porous fabric of cover 57. The heating of the suturing memberalso heat shrinks the sleeve 62. As sleeve 62 shrinks, it reduces in itscircumferential length and uniformly contracts or decreases in diameterabout the valve base 21. This forces the inside portions of cover 57into a firm and uniform frictional engagement with the surface 23 of thevalve base 21. The folded portions of cover 57 behind sleeve 62 causesthe mid-portion of the sleeve to flex outwardly putting longitudinalpressure on flanges 24 and 25. When sleeve 62 is subjected to heat italso elongates in the longitudinal direction forcing ribs 62A and 62Btoward the flanges 24 and 25. This longitudinal expansion of the sleeve62 holds cover 57 in firm engagement with the flanges 24 and 25, therebyeliminating separation of suturing member from flanges 24 and 25. Thewidth and longitudinal length of the ribs 62A and 628 can be varied toregulate the amount of force exerted by the ends of the sleeve onflanges 24 and 25. In other words, the amount of material in the ribs 24and 25. In other words, the amount of material in the ribs 62A and 62Bis a function of the force on the cover portions adjacent flanges 24 and25.

After the plastic core 58 and sleeve 62 are heat cured, the valve 20 andsuturing member 26 are removed from the mold 67. The relatively lowcuring temperature does not have harmful effects on the material of thebase or the disc 22. The resultant suturing member 26 has a continuousand seamless exposed cover 57 since stitches 61 are located behind theheat shrunk sleeve 62. The suturing member 26 is firmly mounted on thebase 21 and permits rotation of the base 21 relative to the suturingmember.

Referring to FIGS. 13 to 18, there is shown another method of making andassembling a suturing member indicated generally at 126 on a valve baseor housing 21. The suturing member 126 has a cover 157. As shown in FIG.12, cover 157 is a seamless cylindrical member of tube cut to a lengthdetermined by the type, size and shape of the suturing member. Cover 157is a seamless tubular knitted or woven Dacron fabric or otherbiologically inert material having mesh, spaces or porosity enablingingrowth of tissue soon after implantation. The seamless cover 157eliminates the side seam shown adjacent stitches 63 in FIG. 6, therebyproviding an even and continuous outer cover surface.

Referring to FIG. 13, an annular core 158 of uncured plastic material,as Silastic, is placed around the outside of a heat shrinkable sleeve162. Sleeve 162 is a tubular plastic member, as Teflon, having annularoutwardly directed ribs 162A and 162B. Sleeve 162 is pre-shrunk on acylindrical mandrel to a selected size or diameter. Cover 157 is placedaround core 158, thereby positioning core 158 between sleeve 162 andcover 157. The plastic material of the core, being uncured andrelatively pliable, does not interfere with the placing of the coveraround the core. Core 158 and sleeve 162 are the same as core 58 andsleeve 62 referred to in FIGS. 1 to 11.

Referring to FIG. 14, the upper and lower ends of cover 157 are turnedin and folded around the sleeve 162 and core 158. This encloses the coreand sleeve within the cover 157. The turned ends of cover 157 arestitched together with stitches 161 adjacent the top side of core 158.

Referring to FIG. 16, the suturing member 126 is then mounted on thevalve base 21. This is accomplished by slipping the sleeve 162 and cover157 over the annular flange 25 to position the sleeve 162 and the cover157 adjacent the sleeve in the annular groove 23 of the base 21 betweenflanges 24 and 25.

The cover 157 is then rotated relative to the core 158 and sleeve 162 inthe direction of arrow 165 shown in FIG. 17 until'the stitches 161 arelocated in groove 23 behind the sleeve 162. Double box stitches 164 and166 are then placed in the cover adjacent opposite ends of sleeve 162.The stitches 164 and 166 have ends (not shown) which are pulled and tiedtogether to firmly anchor the cover on the valve base adjacent theflanges 24 and 25. Stitches 164 and 166 serve as wrappings to insurethat the suturing member 126 will retain its position on the valve base21 and still permit rotation of the valve base 21 relative to thesuturing member 126 after the suturing member has been attached to theheart tissue.

Referring to FIG. 18, there is shown a curing mold 67 for shaping thesuturing member 126 and holding the suturing member during curing ofcore 158. Mold 67 is identical with the mold shown in FIG. 11 and has acenter cavity 68 accommodating the valve 20. The upper portion of cavity68 is enlarged and has an annular stepped groove 69 defining the finalshape of suturing member 126. Annular groove 69 is surrounded by anannular stepped wall 71. Cavity 68 and groove 69 are closed with a flatplate or cover 72. interposed between plate 72 and the outercircumferential portion of suturing member 126 is a ring 73 which has ashape to provide the annular flange 126A of the suturing member 126 witha tapering or narrowing outer peripheral edge. Plate 72 holds the ring73 in engagement with the proximal side of the suturing member 126.Suitable clamp means or fasteners (not shown) secure the plate to themold. The pressure exerted by plate 72 on ring 73 forces the pliableuncured plastic core 158 into surface engagement with the inside surfaceof the fabric of cover 157. The shape of the annular stepped wall andthe surface of the plate along with the shape of ring 73 determine theultimate shape of suturing member 126. Mitral and aortic suturingmembers can be made with molds having different shaped grooves andcontours.

Suturing member 126 is initially pressed into the mold groove 69 tochange the shape of the suturing member to conform to the shape of themold groove. Suturing member 126 is located in the groove with a lightforce fit so that the cover 157 is in a continuous engagement with theplastic core 158. Core 158 is cured by heating the mold for a period oftime. For example, suturing member 126 is heated for about 20 minutes at250 F. Other temperatures and times can be used in accordance with heatcuring characteristics of the plastic core. During heat curing, the corebonds to the inside surface of cover 157 to form a permanent andcontinuous connection or bond 159 between the outer surface of core 158and the inner surface of cover 157. The bond 159, being continuous,eliminates pockets or spaces between the cover and the core. Also, thebond eliminates the possibility of separation of cover 157 from core 158which can provide space for collection of blood or other body fluids.During the heat curing process, the core 158 does not penetrate theporous fabric or cavities of cover 157. Accordingly, the cured core doesnot interfere with tissue ingrowth into the porous fabric of cover 157.The heating of the suturing member also further shrinks the sleeve 162.As sleeve 162 shrinks it reduces its circumferential size and uniformlycontracts or decreases in diameter about the valve base 21. This forcesthe inside portions of cover 157 into a firm and uniform frictionalengagement with surface 23 of valve base 21. The folded portions ofcover 157 behind sleeve 162 causes the mid-portion of the sleeve to flexoutwardly putting longitudinal pressure on flanges 24 and 25. Whensleeve 162 is subjected to heat, it also elongates in the longitudinaldirection forcing ribs 162A and 1623 toward the flanges 24 and 25. Thislongitudinal expansion of the sleeve 162 holds cover 157 in firmengagement with the flanges 24 and 25 thereby eliminating separation ofsuturing member from flanges 24 and 25. The width and longitudinallength of the ribs 162A and 1628 can be varied to regulate the amount offorce exerted by the ends of the sleeve on flanges 24 and 25. In otherwords, the amount of material in the ribs 162A and 16213 is a functionof the force on the cover portions adjacent flanges 24 and 25.

After core 158 and sleeve 162 are heat cured, valve 20 and suturingmember 126 are removed from the mold. The relatively low curingtemperature does not have harmful effects on the material of the base 21or disc 22. The resultant suturing member 126 has a continuous andseamless exposed cover 157 since stitches 161 are located behind theheat shrunk sleeve 162. The cover 157 does not have a longitudinalsleeve as it is formed from a seamless cylindrical or tubular membershown in FIG. 12. The suturing member 126 is firmly mounted on base 21and allows for rotation of the base relative to the suturing memberafter it has been attached to the heart tissue.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A process of making a suturing member and mounting the suturingmember on a device comprising: enclosing within a cover an annularsleeve of heat shrinkable material and a core of uncured plasticmaterial; locating the cover and enclosed sleeve and core around thedevice; forming the suturing member into a desired shape, and heatingthe cover and enclosed sleeve and core to heat shrink the sleeve aroundthe device and cure the plastic material of the core.

2. The process of claim 1 wherein: during the forming of the suturingmember the uncured plastic material of the core is positioned intoengagement with the inside surface of the cover, and during the heatingof the cover the plastic material of the core is bonded to the insidesurface of the cover.

3. The process of claim 1 wherein: a measured amount of uncured plasticmaterial is positioned adjacent the sleeve and enclosed by the cover.

4. The process of claim 1 including: stitching the cover together toenclose the sleeve and uncured plastic material within the cover.

5. The process of claim 1 including: closing the cover by connectingadjacent end portions of the cover together.

6. The process of claim 5 wherein: the connected adjacent end portionsof the cover are located between the sleeve and the device.

7. The process of claim 1 wherein: the suturing member is formed on thedevice by pressing the suturing member into a mold cavity having thedesired shape.

8. The process of claim 1 including: connecting the cover togetheradjacent one side of the core to enclose the sleeve and core within thecover, and locating the connecting portions of the cover between thesleeve and device after the cover and enclosed sleeve and core arelocated on the device.

9. The process of claim 1 including: connecting the end portions of thecover together adjacent the inside of the sleeve to enclose the sleeveand core within the cover.

10. A process of making a suturing member and mounting the suturingmember on a device having an annular outside portion for holding thesuturing member comprising: providing a cover of porous material of asize to be positioned around the device so that part of the cover can belocated adjacent the outside portion of the device; locating uncuredplastic core material and an annular sleeve of heat shrinkable materialadjacent the cover, enclosing the uncured plastic core material andsleeve within the cover in an annular shape, locating the cover andenclosed sleeve and core around the device, forming the suturing memberon the device by pressing the cover and enclosed core of plasticmaterial into a desired shape and positioning the uncured plasticmaterial in engagement with the inside surface of the cover, and heatingthe cover and enclosed core of plastic material and sleeve of heatshrinkable material to cure the plastic material, heat shrink the sleeveand bond the core of plastic material to the inside surface of the coverto maintain the shape of the suturing member.

11. The process of claim 10 wherein: the cover is closed by connectingadjacent end portions of the cover together.

12. The process of claim 10 wherein: the connected adjacent end portionsof the cover are located between the sleeve and the annular outsideportion of the device.

13. The process of claim 10 wherein: the cover is a seamless cylindricalfabric member.

14. The process of claim 10 including: attaching adjacent end portionsof the cover together to enclose the core and sleeve within the cover,and positioning the attached adjacent end portions between the sleeveand outside portion of the device after locating the cover,

sleeve and core around the device.

Patent No. fi fiOOJ'lOfi Dated April 2 197 lnventvfls) Lawi'eficeAndersonl et a1,

' It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Eelurrm line 65, cancel upwardly insert inwardly a Gelunm 7, line 57,.after 26 insert to Calumn 8 lines 8, 9 and 10, after 25, canceiflqnother words, the amount of material in the ribsv 2 and 25".

Signed mid sealed this 10th day of September 19%.

Attesta i MeCUY M. eIBSON, JR; ca MARSHALL DANN I Attesting OfficerCommissioner 'of Patents USCOMM-DC 60378-P69 i Hi5. GOVERNMENT PRKNTINGOFFICE 1969 O3G6-3S4,

1. A process of making a suturing member and mounting the suturingmember on a device comprising: enclosing within a cover an annularsleeve of heat shrinkable material and a core of uncured plasticmaterial; locating the cover and enclosed sleeve and core around thedevice; forming the suturing member into a desired shape, and heatingthe cover and enclosed sleeve and core to heat shrink the sleeve aroundthe device and cure the plastic material of the core.
 2. The process ofclaim 1 wherein: during the forming of the suturing member the uncuredplastic material of the core is positioned into engagement with theinside surface of the cover, and during the heating of the cover theplastic material of the core is bonded to the inside surface of thecover.
 3. The process of claim 1 wherein: a measured amount of uncuredplastic material is positioned adjacent the sleeve and enclosed by thecover.
 4. The process of claim 1 including: stitching the cover togetherto enclose the sleeve and uncured plastic material within the cover. 5.The process of claim 1 including: closing the cover by connectingadjacent end portions of the cover together.
 6. The process of claim 5wherein: the connected adjacent end portions of the cover are locatedbetween the sleeve and the device.
 7. The process of claim 1 wherein:the suturing member is formed on the device by pressing the suturingmember into a mold cavity having the desired shape.
 8. The process ofclaim 1 including: connecting the cover together adjacent one side ofthe core to enclose the sleeve and core within the cover, and locatingthe connecting portions of the cover between the sleeve and device afterthe cover aNd enclosed sleeve and core are located on the device.
 9. Theprocess of claim 1 including: connecting the end portions of the covertogether adjacent the inside of the sleeve to enclose the sleeve andcore within the cover.
 10. A process of making a suturing member andmounting the suturing member on a device having an annular outsideportion for holding the suturing member comprising: providing a cover ofporous material of a size to be positioned around the device so thatpart of the cover can be located adjacent the outside portion of thedevice; locating uncured plastic core material and an annular sleeve ofheat shrinkable material adjacent the cover, enclosing the uncuredplastic core material and sleeve within the cover in an annular shape,locating the cover and enclosed sleeve and core around the device,forming the suturing member on the device by pressing the cover andenclosed core of plastic material into a desired shape and positioningthe uncured plastic material in engagement with the inside surface ofthe cover, and heating the cover and enclosed core of plastic materialand sleeve of heat shrinkable material to cure the plastic material,heat shrink the sleeve and bond the core of plastic material to theinside surface of the cover to maintain the shape of the suturingmember.
 11. The process of claim 10 wherein: the cover is closed byconnecting adjacent end portions of the cover together.
 12. The processof claim 10 wherein: the connected adjacent end portions of the coverare located between the sleeve and the annular outside portion of thedevice.
 13. The process of claim 10 wherein: the cover is a seamlesscylindrical fabric member.
 14. The process of claim 10 including:attaching adjacent end portions of the cover together to enclose thecore and sleeve within the cover, and positioning the attached adjacentend portions between the sleeve and outside portion of the device afterlocating the cover, sleeve and core around the device.